Magnetic recording mediums of the perpendicular magnetization type are roughly classified into two groups. One group consists of those having thin metal films and prepared by depositing a thin metal film of Co-Cr, Fe-Ni-Co, Fe-Co or the like by evaporation, sputtering or other technique on a plastic film base, while controlling the metallizing condition so as to form a readily magnetizable axis perpendicular to the base surface. (Refer, e.g., to Japanese Patent Application Publication No. 91/1983.) The other group mediums have coated films and are prepared by dispersing an acicular magnetic powder of any of the abovementioned alloys in a binder resin, supplying the dispersion to a plastic film base, and then subjecting the coating to magnetic field orientation (e.g., Japanese Pat. App. Public Disclosure No. 111832/1982). In any case, this type has a future possibility in that it can record signals of by far the shorter wavelengths than do the conventional magnetic recording mediums having the easily magnetizable axis in parallel with the base surface. The magnetic recording medium of the perpendicular magnetization type must have a surface smooth enough to minimize the spacing between the magnetic head and the magnetic layer surface. However, such a smooth surface increases friction and presents problems of unintended stop during the travel and unwanted output variations due to irregular winding of the tape. With tapes of this character there is a tendency toward reduction in thickness of the base and the magnetic layer. At present, about 10 .mu.m or thinner bases (e.g., of polyethylene terephthalate, polyethylene naphthalate, polyimides, and polyamides) are under development. These tapes have a soft body and wind too tight on reels. This can lead to deterioration of the tape surface quality with the influence of the rear side properties of the base upon the magnetic coating. Also, adjacent layers of the tape roll can stick together. When the tape is unwound and the base is released out of contact with the magnetic coating of the next tape layer, so-called separation charging can take place, attracting dust and other foreign matter. Sometimes this in turn results in dropouts owing to increased spacing loss. These difficulties have largely offset the advantages of the perpendicular magnetization type magnetic recording medium.